In many cases cancer appears to be the result of inappropriate gene expression. It is the aim of the experiments proposed herein to investigate the mechanisms by which these genes are regulted, to identify the protein products which they may encode, and ultimately to describve the mechanism by which their expression is altered during chemical carcinogenesis. Using BHK cells which have been transformed in a single step in culture by chemical carcinogens, we plan by somatic cell hy brid analysis to determine if the regulation in chemically transfored cells parallels that in RNA virus transfored cells, in human cells and in in vivo-transformed cells. Using a matched homogenius set of normal, transformed, and temperature sensitive BHK cells along with hy brids and segregants derived from them we plan to seek a protein whose pattern of expression can be meaningfully associated with expression of transformation. Using a recently isolated normal BHK line which is unable to suppress transformation as a recipient, we hope to transfer the transformed phenotype va isolated DNA and use this assay to clone the gene responsible for the transformation.